Field of the Invention
The present invention relates to a process for appropriately attaching a slider to a suspension assembly in a magnetic storage system and more specifically to a method for executing an ultrasonic bonding to appropriately attach a slider to a thin multi-piece integrated suspension assembly used in a small-sized magnetic disk storage system and a method for handling the suspension assembly for that purpose.
A magnetic disk drive is an information storage unit using at least one rotatable disk having concentric data tracks including information, a head (or xe2x80x9ctransducerxe2x80x9d) for reading data from or write data in these numerous tracks and a head positioning actuator connected to this head for moving the head to a desired data track and retaining the head on the center of the track during the reading or writing operation. The transducer is mounted on a air bearing slider (hereinafter, simply abbreviated to xe2x80x9csliderxe2x80x9d) and supported near the data surface of the disk by an air cushion generated by the rotating disk. By using the suspension, the slider is mounted on the support arm of the head positioning actuator.
FIG. 1 exemplifies a schematic simplified block diagram of a magnetic disk storage system 40 including a flexure to which a slider is bonded. The magnetic disk storage system 40 comprises at least one rotatable magnetic disk 42 supported on the spindle 44 and rotated by a disk drive motor 46 and at least one slider 48 positioned near the magnetic recording medium on the disk surface 43. Data are stored on the magnetic recording medium on each disk 42 in a ring pattern format of concentric data tracks (not shown). Each slider 48 includes one or more magnetic resistor (MR) sensors and write transducers.
A slider 48 is mounted on an integrated suspension 50 and further the integrated suspension 50 is connected to actuator means 54 by using an actuator arm 52. As a disk 42 rotates, the slider 48 is so controlled by actuator means 54 as to move across means disk surface 43 and the slider 48 accesses or reads a different portion of the disk surface 43 in which desired data are recorded. The integrated suspension 50 gives such a slight spring force as to bias the slider 48 relative to the disk surface 43, thereby controlling a slight vertical elasticity of the slider 48 relative to the rotating disk surface 43. Actuator means 54 as seen in FIG. 1 is, for example, a voice coil motor (VCM). Various components of the magnetic disk storage system 40 are operatively controlled in accordance with a control signal generated by the control unit 56. For example, the operating control of various components includes positioning control of the actuator means 54, motor control of the drive motor 46 and read/write control of data.
The integrated suspension 50 does not only act to dimensionally stabilize the distance between the slider 48 and the actuator arm 52 during the relative movement on the surface of a rotating magnetic disk, but also controls such motions as xe2x80x9cpitch and roll motionsxe2x80x9d (hereinafter, referred to as xe2x80x9cgimbaled motions or gimbal motionxe2x80x9d), among them especially a slight xe2x80x9cvertical motionxe2x80x9d of the slider 48. The xe2x80x9cvertical motionxe2x80x9d in the present specification is to be defined as a motion along a nearly vertical distance between the magnetic disk surface and the air bearing surface of a slider mounted on the suspension when a rotating magnetic disk surface is assumed and the xe2x80x9cvertical directionxe2x80x9d is to be defined as a bidirection toward the magnetic disk surface and toward the air bearing surface of a slider mounted on the suspension. It may be considered to be a direction perpendicular to the air bearing surface.
On pursuing a higher record density, a greater number of data tracks must be packed on the disk surface and the necessity of formatting the disk surface into a narrower data track or into a narrower space between data tracks is urged. To cope with such a challenge, a slider is first downsized. And, it is falling under a category of pico slider. Letting an oblong of 4 mmxc3x972 mm be the standard slider, the pico slider means a slider corresponding to about 30% of its size (about 1.3 mmxc3x970.5 mm). With decreasing area of the air bearing surface of a slider, a force received by the slider from a rotating magnetic disk is necessarily reduced.
Corresponding to such downsizing of a slider, a delicacy will be required concerning the suspension structure, in particular, demand for performance specification concerning a flexure becomes even stricter. Even under a strict tolerance in the alignment of a slider/track, in order that dense stacked data/tracks are accessible and a slider can accurately and repeatedly be positioned to the disk surface, the flexure of an integrated suspension should be strongly built so as to retain the flexibility and reliability even if light/thin.
Since the constitution of an integrated suspension 50 has been improved day by day and various types are present, various names are given even to components of a suspension and are mixed with each other. Accordingly, it has become difficult to precisely call individual pieces with universal names and distinguish them. As one example of constitution among downsized suspensions, however, one comprising a xe2x80x9cload beamxe2x80x9d mounted on the actuator arm of a head positioning actuator and a xe2x80x9cflexurexe2x80x9d supported on the load beam for supporting a slider can be mentioned. The xe2x80x9cload beamxe2x80x9d generally provides an elastic spring action for biasing a slider to the disk surface, whereas the xe2x80x9cflexurexe2x80x9d generally acts to provide flexibility to a slider so that the slider gets on an air cushion close to the rotating disk.
U.S. patent application Ser. No. 08/644878, entitled xe2x80x9cA Multi-Piece Integrated Suspension Assembly for a Magnetic Storage Systemxe2x80x9d, filed 1996-5-10 and assigned to the same applicant as that of the present application discloses a new integrated suspension structure having such a constitution. Here, a thin flexible member and conductive leads are integrally formed. Through the presentation of the suspension structure of this U.S. patent application Ser. No. 08/644878 that has not yet publicly known at the application time of the present invention, embodiments of the present invention will be described.
Meanwhile, for comparison, a conventional suspension structure that has so far been fabricated and a bonding method of bonding pads of a slider and wires which is suitable thereto will be described over FIGS. 2 to 7. The suspension structure here is one example of joined structure of the suspension 50 and the actuator arm 52 of FIG. 1. The wires here and the conductive leads described in the present invention are different in name but identical in the function of making an electrical connection. However, the wires to which a reference is made here as background art differ from conductive leads, are coated with a tube 26 (cf. FIG. 3) for insulation as a separate single piece and are not integrated with a flexible member unlike the present invention.
FIG. 2 is a perspective view showing a conventional head suspension assembly. This head suspension assembly includes a slider 48 and a suspension assembly 12 and a wire assembly 16 and a construction that the wires are retained by caulking at the site 14 is adopted.
FIG. 3 is a plan view showing a wired suspension assembly 20 of background art with a tab structure 22 extending from the suspension assembly 12 provided in consideration of convenience for ultrasonic bonding. This is disclosed in JA 995078 of patent application No. 7-264413 assigned to the same applicant as that of the present application. In this aspect, wires are already stretched and mounted on a suspension assembly. In FIG. 3, however, a slider 48 is not yet mounted unlike FIG. 2 and no slider cannot be seen in FIG. 3. Accordingly, the process of mounting/bonding of a slider will be described.
As shown in FIG. 4, when wires 18 are bridged over a tab 22 and established on a plane parallel to the suspension assembly 12 in a bondable manner, the bonding pads 30 of the slider 48 are established in a manner nearly parallel to the surface of the suspension assembly. As shown in FIG. 5, an ultrasonic bonding tool 32 is also allowed to touch the wires so that the tool surface is nearly parallel to the plane made by these wires, to which a vibration is given almost along a direction 34 in length of the wires. And, after the ultrasonic bonding, the slider is rotated by 90xc2x0 and bonded to the flexure 24 as shown in FIG. 6. In this method, however, something inconvenient occurs. By bending of 90xc2x0 rotation, an excessive portion (wire loop) of the wires 18 appears.
When excessive wires appear, operation of forming the wires 18 becomes necessary. That is because individual wires tend to be stabilized by their (respective convenient) ways of bending and these wires, in general, are not aligned in a uniform way of bending, which tendency exerts a bad influence on various sides. One kind of plastic deformation of wires, e.g., residual stress of wires affect badly. From such a point of view, it is found favorable for the wires 18 that the bondable parts are given by a necessary minimum distance.
Besides, special caution has been demanded for applying a caulking 14 as seen in FIG. 2. This is because wires are excessively pulled in caulking and the effect of pulling reaches the bonded site in the end of the wires. From these, a devise to keep the caulking site 14 apart from the end (portion 18 of wires) is seen. On the other hand, when an attempt is made to keep the caulking site sufficiently distant, there is a possibility of wires to move of itself in the portion to the caulking 14 and this time there is an adverse circumstance that a bad influence arises from another side.
Furthermore, in cases where the whole disk drive system becomes thinner and a stack of integrated suspensions is given to a plurality of disks, it is required to successfully fulfill a mutual connection of leads and a mutual connection of flex cables from the control electronics circuit of a disk drive system and accordingly the need for the adaptation of a vertical height in the stack of actuators occurs.
It follows also from these that the forming of wires is important. That is, the forming of wires becomes important especially as post-process operation for equalizing the way of bending individual wires as well as for confining the extent of individual bends of these wires within a predetermined vertical height. From a change from (a) to (b) of FIG. 7, one approach of forming would be visually understood. Here, by using a forming tool 36 to apply an external force to a wire, the wire loops are evened up.
To improve the mounting manner (attitude) of mounting a slider 48 on the suspension assembly 12 and also to mount a slider 48 on the suspension assembly 12 with so good precision as to maintain a suitable xe2x80x9cstatic attitudexe2x80x9d when the slider 48 is floating over the surface 43 of the rotating disk 42 for a final product, such an operation of forming is important. This is because, if the bending way of individual wires is uneven, the residual stress of wires might cause the static attitude of the slider to be twisted and further a bad effect might appear on the static attitude of the slider later.
Heretofore, methods for bonding a slider to a suspension structure in the background art were described, but as the slider and the suspension structure become super-small and super-fine as with the suspension structure of U.S. patent application No. 08/644878, it becomes difficult to execute the very operation of forming and a proper manufacturing and handling method fit for such a peculiar structure becomes necessary.
It is one object of the present invention to provide a method for performing an ultrasonic bonding of a slider which is suitable to a simplified and new integrated suspension structure relatively easy to manufacture and a handling method for the same.
According to the present invention, a method for performing ultrasonic bonding to a flexure so as to electrically connect a plurality of conductive leads and a plurality of bonding pads of a slider, the flexure including a flexible member and the conductive leads integrally formed thereon, is disclosed which comprises the steps of: positioning bondable parts of the conductive leads to the bonding pads of the slider corresponding to the conductive leads; supporting a part of the flexure close to the bondable parts of the conductive leads so as to restrict a vertical motion of the flexure; and performing ultrasonic bonding between the bondable parts of the conductive leads and the bonding pads of the slider in close order of distance to any of said supported part.
In addition, according to the present invention, a method for transforming, retaining the transformation of and releasing the transformation of a suspension assembly includes a load beam permanently bent at a predetermined part with a predetermined angle and a flexure fixedly attached to a section of the load beam, the load beam having a tab extending beyond the flexure is disclosed which comprises the steps of: applying an external force to the suspension assembly so as to transform in a different angle from the predetermined angle; retaining the transformation of the suspension assembly at the different angle; and releasing the suspension assembly from the retaining the transformation of the suspension assembly, without supporting the flexure, but with supporting the tab of the load beam.
For a fuller understanding of the nature and advantages of the present invention, reference should be made to the following detailed description taken in conjunction with the accompanying drawings.